The most obvious kudo for this mechanical pencil is the comfort factor. As a bookkeeper, comfort is number one on my list of needs for pencils and pens. The barrel is ergonomically designed and is covered with a smooth, rubber grip. I'm completely spoiled now by these new-design writing instruments with fatter barrels. I can hardly hold a regular sized pen or pencil anymore. The new design is the best thing to happen to pens and pencils since their invention, in my opinion.
There are two more features that make the Pentel Quicker Clicker my favorite, though. One is the side lead advance button. It is right there for my thumb to click as soon as the lead runs low without ever disrupting my flow of writing; and the second is the fantastic quality eraser. I love that it never smears, but just erases cleanly and effortlessly.
All in all, this is the writing instrument I've come to depend on and I make sure to mark all mine with my name in permanant ink as soon as I get them so they don't end up in some one else's pocket at work!